Ultrasound and salt reduction effect on physicochemical and rheological properties of meat emulsions.

Power ultrasound and salt reduction effects on meat emulsions' physicochemical and rheological properties were determined. Therefore, meat emulsions with different NaCl concentrations (1, 1.5, 2, and 2.5%) were treated in an ultrasonic bath (40 kHz, 200 W, & 9.34 W/cm2 ) at different times (0, 15, and 45 min). Results showed that salt reduction and ultrasound time significantly (p < 0.05) affected the cooking loss, water holding capacity, water activity, pH, color, hardness, viscosity, storage modulus (G'), loss modulus (G″), and phase angle δ. Meat emulsions with low salt content (1 and 1.5% NaCl) showed significantly higher values of cooking loss than standard emulsions (2.5% NaCl), while ultrasound duration of 15 min reduced the cooking loss (12 to 27%). Hardness, color, pH, and water activity (aw) decreased with salt reduction. Ultrasounds increased the hardness, viscosity, G', and G'' values in reduced-salt meat. The experimental data of apparent viscosity were properly fitted to the mathematical model of Ostwald-de-Waele. Ultrasound increased consistency (k) and decreased flow behavior index (n) in emulsions with 1.5 to 2.5% NaCl. Ultrasound at 15 min induced gelation in emulsions with 1.5 and 2.0% NaCl (40 and 20% NaCl reduction). The formulation with 2.0% NaCl was found to be the maximum concentration that did not sacrifice meat emulsion quality. When combined with 15 min of ultrasound, this formulation yielded results comparable to the standard formulation. PRACTICAL APPLICATION: Results contribute to developing reduced-salt meat emulsions using power ultrasounds. Therefore, using ultrasounds allows for a 20% reduction in salt content while maintaining the quality of the meat emulsion.

Changes in phenolics and flavonoids in amaranth and soybean sprouts after UV-C treatment.

Sprouts, mainly from cereals, legumes, and some pseudo-cereals, are rich in nutrients and contain biocompounds, making them attractive for consumption. This research study aimed to develop treatments with UV-C light in soybean and amaranth sprouts and evaluate their effect on biocompounds content, compared with chlorine treatments. UV-C treatments were applied at distances of 3 and 5 cm and times of 2.5, 5, 10, 15, 20, and 30 min, whereas chlorine treatments were applied as immersion in solutions at 100 and 200 ppm for 15 min. Phenolics and flavonoid content were higher in UV-C-treated sprouts than in those treated with chlorine solutions. Ten biocompounds were identified in soybean sprouts, with increasing in apigenin C-glucoside-rhamnoside (105%), apigenin 7-O-glucosylglucoside (237%), and apigenin C-glucoside malonylated (70%) due to UV-C application (3 cm, 15 min); for amaranth sprouts, five biocompounds were identified, with higher contents of p-coumaroylquinic acid (17.7%) after UV-C treatment (3 cm, 15 min). The best treatment to achieve the highest bioactive compounds concentration was UV-C at a distance of 3 cm for 15 min, without significant modification on the color parameters, Hue and chroma. PRACTICAL APPLICATION: UV-C can be used to increase the biocompound content in amaranth and soybean sprouts. Nowadays, there is UV-C equipment available for industrial applications. In this way, sprouts may be maintained as fresh through this physical technology, and they will retain or increase the concentration of health-related compounds.

Natural Antimicrobials: A Clean Label Strategy to Improve the Shelf Life and Safety of Reformulated Meat Products.

Meat is a nutrient-rich matrix for human consumption. However, it is also a suitable environment for the proliferation of both spoilage and pathogenic microorganisms. The growing demand to develop healthy and nutritious meat products with low fat, low salt and reduced additives and achieving sanitary qualities has led to the replacement of the use of synthetic preservatives with natural-origin compounds. However, the reformulation process that reduces the content of several important ingredients (salt, curing salts, etc.), which inhibit the growth of multiple microorganisms, greatly compromises the stability and safety of meat products, thus posing a great risk to consumer health. To avoid this potential growth of spoiling and/or pathogenic microorganisms, numerous molecules, including organic acids and their salts; plant-derived compounds, such as extracts or essential oils; bacteriocins; and edible coatings are being investigated for their antimicrobial activity. This review presents some important compounds that have great potential to be used as natural antimicrobials in reformulated meat products.

Development of Healthier and Functional Dry Fermented Sausages: Present and Future.

In recent years, consumer perception about the healthiness of meat products has changed. In this scenario, the meat industry and the scientific and technological areas have put their efforts into improving meat products and achieving healthier and functional formulations that meet the demands of today's market and consumers. This article aims to review the current functional fermented meat products, especially on sausage development. Firstly, an emphasis is given to reducing and replacing traditional ingredients associated with increased risk to consumer's health (sodium, fat, and nitrites), adding functional components (prebiotics, probiotics, symbiotics, and polyphenols), and inducing health benefits. Secondly, a look at future fermented sausages is provided by mentioning emerging strategies to produce innovative healthier and functional meat products. Additional recommendations were also included to assist researchers in further development of healthier and functional sausages.

Influence of fat content and water activity on the heating pattern of model systems submitted to microwave heating.

This research analyzed the influence of fat content (1%, 3%, 5%, and 10%, w.b.) and of water activity (0.85, 0.90, 0.95, and 0.99) on the effectiveness of microwave heating within model systems (agar gel). Findings indicate that an increased fat content promotes more uniform heating in the model systems and results in longer heating times to reach the target temperature of 50°C. In the model systems with different aw values, the warming of the central model zone was slower while in the corners, heating was accelerated. Additionally, in these models, heating times increased as the aw was decreased. PRACTICAL APPLICATION: The study of model systems allows for a detailed assessment of food when subjected to microwaves; and how heating is influenced by food properties such as aw and fat content. Findings indicate that changes in product formulation could improve the heating of ready-to-eat foods, either by increasing the fat content (better uniformity) or having high aw (shorter heating time).

Dielectric characterization of vegetable oils during a heating cycle.

The knowledge of the dielectric properties of oils is of great importance for several industrial applications, such as microwave-assisted oil frying for foods and high voltage electric power transmission. In this paper, we present the complex permittivity of vegetable oils (canola, olive, soybean, coconut) at 2.50 GHz using the cavity perturbation technique from 28 to 200 °C (temperature close to the smoking point of oils). The measurements were taken with a cylindrical cavity operating at the TE111 mode with an unloaded Q of 4950. In addition, free fatty acids, peroxide index and color were measured before and after heating.

Dielectric properties of fresh rabbit meat in the microwave range.

Dielectric properties (DPs) of fresh rabbit meat in the microwave range (0.5 to 20 GHz) were determined. Three different muscles (Biceps femoris, Tensor fasciae latae, and Longissimus thoracis) from California rabbits (male and female) were measured with the open-ended coaxial probe method at temperatures of 20, 40, and 60 °C. To assess the possible effect of age, females of 100 and 180 days old were analyzed. DPs were affected by frequency, muscle type, age, gender, and temperature (p < 0.05). Dielectric constant decreased with increasing frequency. Loss factor decreased from 0.5 to 2.5 GHz due to ionic conduction, followed by an increase up to 20 GHz, dominated by dipolar relaxation. PRACTICAL APPLICATION: These results are key parameters for further quality sensing applications and for heating processes of meat rabbit using microwaves. Longer penetration depths were achieved at 915 MHz; this frequency is recommended for further applications. Besides, dielectric properties have potential to be a tool for identification of gender and age for slaughtered rabbits.

Plant Extracts Obtained with Green Solvents as Natural Antioxidants in Fresh Meat Products.

Plants are rich in bioactive compounds (BACs), mainly polyphenols, which are valuable choices to replace synthetic antioxidants in meat products. These natural antioxidants from plants, in the form of extracts and essential oils (EOs), have been obtained from different sources such as fruits (dragon fruit, guarana, pomegranate), vegetables, (cabbage, onion), herbs, and spices (epazote, ginger, rosemary, sage, thyme, turmeric, winter savory) by several extraction processes. However, in the context of current directives there is a notable incentive for "green" solvents to replace organic ones and conventional techniques, in order to avoid harm to the environment, operator, and consumer health. In addition, the recycling of co-products from the processing of these plant materials allow us to obtain valuable BACs from under-exploited materials, contributing to the revalorization of these wastes. The resulting extracts allow us to maintain the quality of meat products, exhibiting similar or better antioxidant properties compared to those shown by synthetic ones. Their incorporation in fresh meat products would maintain the oxidative stability, stabilizing colour parameters, decreasing the formation of metmyoglobin, lipid, and protein oxidation and the generation of lipid-derived volatile compounds, without affecting sensory attributes. In addition, these novel ingredients contribute to improve both technological and functional characteristics, thus diversifying the offer of so-called "wellness foods". In this review, the application of plant extracts as natural antioxidants in several fresh meat products is presented, showing their efficacy as scavenging radicals and imparting additional health benefits.

Dielectric properties of Mexican sauces for microwave-assisted pasteurization process.

The dielectric properties and specifically the complex relative permittivity of foods are key elements for the design of pasteurization processes with high frequency electromagnetic waves. Mexican sauces are recognized worldwide for their flavor and nutritional properties. In this work, the complex permittivity of four of the most representative sauces of Mexican cuisine (chipotle chili, habanero chili, red and green sauce) is presented. The permittivity was measured with the open coaxial probe method at temperatures of 25, 40, 55, 70, 85 °C and in the frequency range of 500 MHz to 6 GHz. Additionally, moisture content, specific heat, viscosity, water activity, density and electrical conductivity are reported, these last three at 25 °C. Dielectric properties were affected by the sauce formulation. The loss factor of each sauce sample at any temperature presents significant changes in relation to the frequency. At 915 and 2,450 MHz, d ε ' ' d T > 0 , which would cause a thermal runaway effect or the uncontrolled rise in temperature in the sauces during the microwave pasteurization. At 5,800 MHz, d ε ' ' d T < 0 , which would give better control for microwave heating than at 915 and 2,450 MHz. At 915 MHz, the loss factor of all sauces is higher than at 2,450 and 5,800 MHz, therefore, more rapid heating can be produced. Moreover, at 915 MHz, microwaves exhibit higher penetration depth than at 2,450 and 5,800 MHz; therefore, at 915 MHz, the greatest uniform microwave dielectric heating would be achieved. Thus, 915 MHz is the frequency recommended for the studied sauces pasteurization. PRACTICAL APPLICATION: This work provides the dielectric properties of Mexican sauces at different temperatures and their penetration depths in the microwave range, which are key information for further microwave-assisted pasteurization process and for getting safer sauces for consumers. Moreover, this research supplies suggestions about what frequency for ISM (Industrial, Scientific and Medical) applications is the best for microwave-assisted pasteurization according to the penetration depth of the electromagnetic wave in the sauces and microwave dielectric heating speed of the sauces.

Dielectric properties of litchi fruit (Litchi chinensis Sonn) at microwave frequencies.

The dielectric properties of litchi fruit were determined using the open-ended coaxial probe method. The measurements were performed in the frequency range from 0.5 to 20 GHz during 3 days of storage at room temperature (~  24 °C). The dielectric properties increased with storage time. Additionally, measurements at different temperatures (24, 30, 40 and 50 °C) were determined. The dielectric constant (ε') decreased with increasing temperature in a frequency range of 0.5-5 GHz; at higher frequencies, ε' increased with increasing temperature. The loss factor (ε″) value increased at frequencies higher than 2 GHz and decreased with increasing temperature. The results will be useful for further applications using microwaves, such as microwave-assisted drying, sensing of quality parameters, modeling, and heating to protect against molds or insects, among other applications.

Dielectric Properties of Beverages (Tamarind and Green) Relevant to Microwave-Assisted Pasteurization.

Dielectric properties (DPs) of two beverages, tamarind and a green drink (based on mix fruits of pineapple, guava, lemon, and nopal), were studied. The DPs were determined using the open-ended coaxial probe method in the frequency range from 0.25 to 25 GHz at 10, 30, 50, and 70 °C. The dielectric constant decreased when both frequency and temperature increased above 1000 MHz. For both beverages, the dielectric loss factor increased with increasing frequency and increasing temperature. In addition, dielectric constant values ranged from 59.7 to 82.5, and the dielectric loss factors were between 5.8 and 31.1. The penetration depth (dp ) of electromagnetic waves in the beverages increased proportionally to temperature at frequencies above 1000 MHz; dp values ranged from 0.2 to 7.5 cm. Because of its complexity and the amount of ingredients and the interactions between them, the green drink showed higher values of dielectric constants in comparison with the tamarind beverage. PRACTICAL APPLICATION: The dielectric properties of the studied beverages, how they behave at different temperatures, and the penetration depth reached by microwave at the allocated frequencies, provide important parameters for further heating treatments, such as heating (microwave-assisted pasteurization) and for modeling/simulation purposes.

Dielectric characterization of raw and packed soy milks from 0.5 to 20 GHz at temperatures from 20 to 70 ºC.

For microwave heating pasteurization processes, knowledge of the dielectric characteristics of foods are very important. In this paper, we present the dielectric properties of raw soy milk and commercial packed soy milk of four different flavors (light, natural, chocolate and pecan) from 500 MHz to 20 GHz, covering most of the assigned frequencies by the Federal Communications Commission for heating purposes. Experiments were performed using an open-ended-coaxial probe and a vector network analyzer. This characterization was carried out for temperatures ranging from 20 to 70 °C in steps of 10 °C. The dielectric constant of soy milks decreased with increasing frequency, while increasing temperature resulted in decreasing of the values. The dielectric loss factor presents a U shape behavior, where the loss started decreasing from 500 MHz to about 3 GHz and then, it increased again up to 20 GHz. In addition, higher temperatures decreased the dielectric loss. Applying the higher order Debye´s equation, two relaxation times were calculated for the soymilks, with good agreement with the measured properties. Deeper penetration of microwaves were obtained for raw soy milk at 915 MHz, making it suitable for microwave pasteurization.

Effects of microwave-assisted hot water treatments designed against Mexican fruit fly (Anastrepha ludens) on grapefruit (Citrus paradisi) quality.

BACKGROUND: Hot water treatment (HWT) against Anastrepha ludens was developed achieving 48 °C in the core of grapefruits and holding it for 6 min. After heating, the grapefruits were hydro-cooled and stored at 23 °C and analyzed for 16 days. The effect of microwave-assisted HWT (MW-HWT) on grapefruit quality was analyzed and compared with the quality of fruits treated with HWT and control fruits (without treatment). The physicochemical properties and chemical composition of essential oil were analyzed. RESULTS: MW-HWT was equivalent to HWT according to accumulated heat calculations, with the advantage of being shorter. Treatments significantly affected the weight, color, maturity index, juice content, firmness, titratable acidity, pH, and ascorbic acid content of the grapefruits (P < 0.05), but had no effect on the total soluble solids (P > 0.05). The major components identified in the essential oil were d-limonene and ß-myrcene, compounds responsible of the scent of the grapefruits. CONCLUSION: MW-HWT was shorter (130 min) and had a lesser effect on the quality of the grapefruit when compared with fruits under HWT (188 min duration). Thus, this treatment could be considered as an alternative method against the Mexican fruit fly in grapefruit. © 2017 Society of Chemical Industry.

Dielectric properties of cereals at frequencies useful for processes with microwave heating.

Dielectric properties of barley, corn (white and yellow), sorghum, and wheat at microwave frequencies for heating purpose were analyzed. Properties were determined at 915, 2450 and 5800 MHz with the free space transmission method in the cereals at 20, 30, 40, 50 and 60 °C. ε´ and ε"of all the cereals decreased with increasing frequency. ε´ slightly increased with temperature, while ε "remained practically constant for all the cereals in the temperature range from 20 to 60 °C. Penetration depth decreased with increasing frequency for all the samples, and increased with increasing temperature at 915 MHz, except for barley. These results are useful for further microwave heating applications for the studies on cereals.

Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes.

Effect of the addition of basil essential oil on the degradation of palm olein during repeated deep frying of French fries.

The potential antioxidant power of basil essential oil under frying conditions was explored. Two concentrations (200 or 500 ppm) were added to palm olein (PO) to evaluate their effect on fat oxidation/degradation during repeated frying of French fries at 180 °C. A higher oxidative stability index was detected for PO with basil essential oil at 200 ppm. Both concentrations showed lower p-anisidine values than PO without basil essential oil after 5 d of frying. Addition at 500 ppm resulted in the lowest total polar compounds and free fatty acids contents. Thus, the addition of basil essential oil improved the performance of PO during repeated frying of French fries.

Thermal inactivation of Salmonella enteritidis PT 30 in almond kernels as influenced by water activity.

Salmonellosis outbreaks related to consumption of raw almonds have encouraged the scientific community to study the inactivation kinetics of pathogens in this dry commodity. However, the low moisture content of the product presents a challenge for thermal control, because the time required to achieve the desired thermal inactivation of microorganisms increases sharply with reduced moisture content and water activity. In this study, we explored and modeled the heat inactivation of Salmonella enterica serovar Enteritidis PT 30 in almond cultivar 'Nonpareil' kernel flour at four water activity (a(w)) values (0.601, 0.720, 0.888, and 0.946) using four temperatures for each a(w). The results showed that the inactivation was well fitted by both Weibull distribution (R(2) = 0.93 to 1.00) and first-order kinetics (R(2) = 0.82 to 0.96). At higher a(w) values, the rate of inactivation increased and less time was needed to achieve the required population reduction. These results suggest that, to avoid deterioration of product quality, shorter process times at lower temperatures may be used to achieve desired inactivation levels of Salmonella Enteritidis PT 30 by simply increasing the moisture content of almonds. These goals could be achieved with the use of existing procedures already practiced by the food industry, such as washing or prewetting scalding before heat inactivation.

Microwave-assisted extraction of essential oils from herbs.

Microwave-assisted extraction (MAE) has been recognized as a technique with several advantages over other extraction methods, such as reduction of costs, extraction time, energy consumption, and CO2 emissions. In this study, MAE was performed to obtain essential oils from two different herbs (basil and epazote). A factorial design was conducted in order to determine the effect of solvent quantity, power, and heating time on essential oil yields. Chemical composition, physical properties and yield percentage of essential oils from MAE were compared with essential oils obtained by steam distillation (SD). Amount of solvent and heating time significantly affected the yields (p < 0.05). Chemical composition and physical properties of the essential oils from basil and epazote were not affected by the extraction method (MAE or SD), with similar yielding obtained by both methods (p < 0.05).

The effect of food type (fish nuggets or French fries) on oil blend degradation during repeated frying.

UNLABELLED: Oil that is reused multiple times for deep frying goes through changes in chemical composition and physical characteristics, affecting the quality of the fried foods. In this study, the effect of the food type (fish nuggets or French fries) on the degradation of an oil blend during the deep-fat frying of each food at 180°C during 12 days was determined, and the characteristics of the fried products were evaluated. The degradation of oil during repeated use was relatively faster when fish nuggets were fried than when French fries were fried, as higher values of total polar compounds were obtained. PRACTICAL APPLICATION: The results are useful for producers of French fries and fish nuggets, such as restaurants or fast foods sellers, providing them with practical guidelines within the permitted values established by the regulatory authorities. The studied foods have high economic importance and are different in their composition. Under the studied conditions, the tested oil blend may be used during 4 d (4 h per day) with a daily replenishment, without discarding the oil when frying fish nuggets, and must be discarded after 8 d when French fries are processed. This suggestion allows preparing safe fried foods for consumers.

Hot water bath treatments assisted by microwave energy to delay postharvest ripening and decay in strawberries (Fragaria × ananassa).

BACKGROUND: A lab-scale approach using microwave (MW)-assisted hot water treatments was developed and tested to assess the potential of this heating method to delay postharvest ripening and decay in strawberries. Strawberries (Fragaria × ananassa) immersed in water were exposed to microwaves at a frequency of 2450 MHz for 3 min at 514 W or 1 min 50 s at 763 W to reach an average temperature of 43.8 ± 0.6 °C at the fruit centre. Another batch was treated in hot water at 45 °C for 15 min, and a final batch was not treated (control). RESULTS: After 9 days of refrigerated storage (3 °C and 90% relative humidity), all heat-treated strawberries showed significant retention of quality parameters such as colour and firmness and significantly lower yeast and mould populations (P < 0.05). CONCLUSION: Strawberries subjected to MW-assisted hot water treatments showed significantly better retention of lightness compared with conventionally treated berries. A short (1 min 50 s) treatment at 763 W was the best choice to prevent strawberry decay.